Drier drum having keat-exchangefluid supply and removal means



2 Sheets-Sheet vl Dec. 3l, 1946. L. HoRNBosTEL l DRIER DRUM HAVINGHEAT-EXCHANGE-F'LUID SUPPLY AND REMOVAL MEANS Filed April 1o, 1944 Dea31, 1946- l l.. HoRNBosTEL 2,413,567

DRIER DRUM HAVING HEAT-EXCHANGE-FLUID SUPPLY AND REMOVAL MEANSFiledApril 10, 19.44 2 Sheets-Sheet 2 Patented Dec. 31, 1.946

DRIER DRUM 2,413,567 HAVING HEAT-EXCHANGE- FLUID SUPPLY AND REMOVALMEANS moya nombostel. Beloit, wis., assignmto Beloit Iron Works, Beloit,Wis., a corporation of Wisconsin Application April 10, 1944, Serial No.530,373

6 Claims.

1 This invention relates to a rotatable drum structure that is heatedwith a vaporized material thatl boils at high temperatures, Moreparticularly this invention relates to a drier drum fora paper makingmachine and to means for heating the drying surface of the drum with ahigh temperature boiling material that has been transformed into a vaporby subjecting the material to high pressure or superheated steam in achamber*v that is located outside the drum.

'This application is a continuation-in-part of my copending applicationSerial No. 480,054, filed' March 22, 1943. entitled Drier drum, nowPatent No. 2,365.2'71.

While this invention has been disclosed herein as embodied in the drierdrum of a paper making machine, itis not intended to in any way limitthe structure to this type of drum since the improvements are equallyapplicable to many types of drums in the other arts.

Heretofore, in order to attain a rapid drying capacity for a drier drumin certain types of paper making and other machines wherein a singiedrum of large size is employed, it has been the practice to use highpressure steam in the drum as the heat transfer medium therefor. butthis has required a thickening of the drum wall in order to withstandsuch internal high pressure to which the drum is subjected. This thickwall structure results in a decrease in the heat transfer through thewall to the paper sheet or other web thereon. and the heavier wall alsoplaces a higher load upon the drum actuating devices thereby requiringan increased power to rotate the drum. i

The present improvements aim to overcome the conditions above mentionedby providing a high pressure steam boiler exterior to the drum forheating and vaporizlng a high boiling point material. and thentransferring this vaporized material which is at a relatively lowpressure, to the interior of the drum to transfer heat to the surfacethereof. The products of condensation of this vaporized material thataccumulate on the walls of the drum are removed and are returned to thehigh pressure steam boilerfor reheating,

,revaporizing and recircuiating it, By using a high boiling point heattransfer liquid material the steam boiler may be charged with highpressure steam at a temperature up to around 850 pounds per square inchpressure to heat and transform the liquid high boiling heat transfermaterial into a vapor that is characterized by its high temperature aswell as its low pressure which will be only slightly above atmosphericpressure. As a result thereof, the drum structure 2 may be madecomparatively light since it is not subjected to high internal pressure.

In carrying out this invention it is contemplated to use a high boilingpoint material such as that commercially known as Dowtherm" which is-aeutectic mixture of diphenyl and diphenyl oxide. This material is arelatively inert,

colorless and non-corrosive liquid that is stable pressure boiler unitfor revaporization and recir.

up to 725 C. and has a boiling point of 258 C. with a heat vaporizationof 123 B. t. u. per pound at its boiling point.

Itis one of the principal objects of this invention to simplify theconstruction of a drier drum such as, contemplated herein and to improvethe efiiciency, operation and dependability of such drier drum.

Another principal object of this invention resides in the provision of ahigh pressure boiler heating unit wherein the heat transfer medium isheated and vaporized at a location outside the drum to be heated, andthen discharging such vaporized medium into the drum through a trunnionthereof to bring this hot vaporized material into heat exchange relationwith the drum wall. The invention also contemplates the condensing ofthe vaporizedheating medium upon the walls oi the drum to be removedtherefrom into a stationary tray or basket that is disposed axially ofthe drum, and then conveying the condensate out of the drum forreturning it again to the high culation.

Another object of the invention aims to utilize super-heated orhigh-pressure steam to heat and vaporize a high boiling point heattransfer liquid for charging a drier drum of a paper making machinewhereby the drum is maintained at a desirable high degree of temperaturewithout subjecting the drum to a high internal pressure.

It is a further object of the invention to provide i means for removingor exhausting air that may accumulate within the upper segment of thedrum thereby preventing the formation of an air pocket that mightinterfere with or prevent uniform heating of the drum surface upon whichthe paper is carried.

Another object of the invention is to provide a dipper device coactingwith but spaced from the inner surface of the drum, said 'clipper beingadapted toscoop up the condensate material from the drum surface anddeposit it into a tray or basket within the drum. Scraper means aremounted on the tray or basket to terminate closely adjacent the drumwall to sweep the interior surface of the drum at a position between thelines of travel 0f a pair of spaced dippers. Spacing of the dippers andscrapervfrom the drum surface permits the heating material to contactal1 of the cylindrical part of the drum-thereby preventing formation ofzones on the cylinder which are at different temperatures than the restof the cylinder.

Additional objects, aims and advantages of the invention such ascontemplated herein will be apparent to persons skilled in the art afterthe construction and operation of the drier drum is understood from thewithin description.

It is preferred to accomplish the numerous objects of this invention andto practice the same in substantially'the manner hereinafter fullydescribed and as more particularly pointed out in the claims. Referenceis now made to the accompanying drawings that form a part thereof.

Figure 1 is a vertical longitudinal section through the axis of a drierdrum structure showing the instrumentalities of this inventionincorporated therein;

Figure 2 is a vertical transverse section of the drier drum taken alongthe plane of line II--II on Figure l; and

Figure 3 is a diagrammatic view illustrating the manner of vaporizingand circulating the heat transfer material, the evacuation of'condensateliquid from the drum, and the other instrumentalities of the presentinvention.

The drawings are to be understood as being more or less of a schematiccharacter for the purpose of disclosing a typical or preferred form ofthe improvements contemplated'herein.

The drier drum according to the invention is designated as a whole byreference numeral I0, and is shown to comprise a cylindrical wall IIhaving end walls or heads I2 and I3 that preferably bulge inward asshown in Figure 1. The web or sheet of paper to be dried is receivedupon and usually travels with the outer surface of the cylindrical WallII. The end walls or heads are provided with axially disposed hollowhubs I4 and I5, respectively.

The trunnions of the drum comprise tubular members I6 and I1,respectively, that have flanged end portions IBa and I1a, respectively,and are bolted to the end walls or heads I2 and I3 in surroundingrelation with respect to the hubs I4 and I but spaced therefrom. Thetrunnions I6 and I1 are rotatably mounted in anti-friction bear- `ingsI8 carried in journal housings I9 that are supported upon the upperportionsv of pedestals 20. The drum is rotated by means of a large gear2I that is secured to the trunnion I1 and actuated by any suitable primemover.

The end walls or heads I2 vand I3 of the drum are exteriorly coveredwith insulating material 22 that is held in place and protected by meansof retainer plates 23. The hollow hubs I4 and I5 of the end walls orheads are sheathed with insulating material 24 that is held in place bycylindrical retainers 25. Suitable access openings 26 are provided inconvenient portions of the heads I2 and I3, and these openings areclosed by caps or covers 21 that are lined with insulating material 28.Cooling fins 29 project from the flanges I6a and I1a of the trunnionsand between these ns the trunnions are provided with apertures 30 thatpermit coolant air to enter the trunnions to circulate between them andthe insulated hubs I4 and I5 of the heads of the drum. The cylindricalwall II of the drum is an effective heat transfer metal that is adaptedto retain its shape during the repeated heating and cooling thereof thattakes place between the Operating 3|,l and the shut-down periods of themachine. By reason of the above mentional insulating arrangement ,andthe cooling of the hub, the cylinder II will be the only heat radiatingsurface of the drum and it therefore may be made of a relatively thinmetal because it is not subjected to internal high pressure due to theuse of a heat transfer material that vaporizes at a high boiling point.

A comparatively shallow tray or basket 3I is disposed within the drumand it is of a Width to extend across the diameter of the drum in themanner shown in Figure 2 to space its ends from the inner surface ofthedrum. l

The tray has a trough-shaped bottom portion 32 the outer portions ofwhich are down-turned as at 33, and its edges are connected to suitableend walls 34. A depending rib 35 extends along the lower portion of thetray bottom wall to reinforce and strengthen the tray structure. 'I'heend walls 34 of the tray are suitably secured to annular fianges 35 uponthe inner ends of tubular members 31 and 38 that freely pass through thehubs I4 and I5 of the respective heads I2 and I3 of the drum so thattheir other ends project beyond the ends of said hubs as shown '1nFigure l.

The outer end portion of the tubular member 31 is iixedly mounted in asupport 39 on a pedestal 40, and the'outer end of the other tubularmember 3B is iixedly mounted in a support 4I upon a pedestal 42 that islocated beyond the 4driving gear 2|. The supports 39 and 4| grip thetubes 31 and 38 to support them in spaced relation to the hubs I 4 andI5 that rotate free thereof. This arrangement provides a fixed exteriorsupport for the tray or basket 3l that is Within the drum and it alsoprovides annular passageways 43 and 44 in the clearances between thetrunnions and the tubes.

'I'he tray end wall 34 that is secured to the tube 38 has an aperture 45at least the major portion of which is disposed abcvethe axis of saidtube, and the other end wall 34 of the tray that is secured to the tube31 has an opening 46 ytherein that is preferably co-extensive with theinterior bore of the tube 31. A scraper or doctor 41 projects from themid-portion of a margin of the tray into close proximity to the innersurface of the drum for the purpose of directing condensate swept by itfrom the drum into the tray. The liquid is drawn ofi' the tray throughthe large aperture 48 and flows through the tubular member 31. At itsouter end the tubular member 31 communicates with a drain-pipe 43 thatconveys the condensate to an accumulator or tank 49.

The outer end o'f the tubular member 38 communicates with a nozzle 50 ontheA support 42 that receives the heat transfer material in a vaporizedform 'at relatively low pressure from a. .conduit 5I that leads theretofrom a vapor chest or boiler 52. This vaporized material is dischargedinto the drum through the aperture 45 in the tray end wall. The lowerportion of the end w'all below the aperture 45 provides a dam 53 thatprevents the flow of liquid from the tray into the tubular member 33through which the vapor passes.

*For the purpose of evacuating air from the upper portion of the drum toprevent formation of an air pocket therein, a, suitable air exhaust pipe54 is disposed in the cylinder with its upper chest 52 comprises aclosed shell vthat surroundsy a coil 59 in Ywhich super-heated orhigh-pressure steam is circulated from any suitable source. The heattransfer material in a liquid form is contained in the shell where itsurrounds the coiil 4 59. The temperature of the heat transfer materialis thus raised above its high boiling point to vaporize it, and thisvapor leaves the boiler shell through a feed pipe 5I that conveys thevaporized -material to the nozzle 50 for discharging it into' the drumthrough the tube 38 andthe opening 45 in the end wall of the tray.

Thecondensate that accumulates in la iilm upon the interior. surfaceoi.' the drum is removed therefrom by the scraper or doctor 41 and iiowsinto the tray or basket 3|. Suitable concave or pocket-shaped dippers 60are carried by brackets 3| that project inward from the heads I2 and I3of the drum and are disposed with their lip portions close to the insidesurface of the drum to scoop up the condensate liquid that forms apuddle in the bottom or lower segment of the drum during its rotation.'I'he scoops or dippers travel with the drum and they are arrangedpreferably in pairs at diametrically opposite portions of the drum, andbeing in non-contacting relation to the inner surface of the cylinder IIthey do not interfere with the heating of the drum surface. apart adistance that permits them to clear the end edges of the scraper 41 whenthe drum is The dippers of each pair are spaced.'

operating. These dippers 60 are adapted to spill the condensateliquidlnto the tray or basket 3I after they have traveled above thehorizontal plane of said tray. The superficial area of the tray issufiicient to receive any drip 0f the con..

densate that may gravitate from or -be thrown off during rotation of thedrum. The liquid of condensation passes out of the tray through thelarge aperture 46 in its end Walland flows into tubular member 31 fromwhich it is removed by the drain-pipe 48 that discharges into theaccumulator 49. From .the accumulator the condensate liquid is returnedto the steam chest or boiler by means of a fluid pump B2 and a returnpipe E3. This arrangement is effective for the recirculation and therevaporization of the heat transfer material. r

An annular seal casing 64 is carriedby the end `iace of the hub I5 torotate with lthe drum in surrounding rel-ation to the end portion of thestationary'tubular member 38. Within this casing the tubular member 38has an annular collar 65 secured to it that has a radial bore B6 alinedwith a hole in this tubular member.v An elbow coupling 81 is threadedinto the hole to establish communication between the radial bore and asuction pipe 68 that extendsout of the supported end of the tubularmember 38 and through a gland 59 in the wall of the nozzle 50 and thenceto the condenser 51. A pair of spaced diaphragm rings 10 are carried bythe inner surface of seal casing 64 and extend inwardly toward and pastthe outer face of the collar 95 on tubular member 38 where they areprovided with seal rings 1I vthat slidably engage or oppose the sideface oi' said collar to bear against them in sealingr relation. Thespacing of these diaphragm rings 1I! provides between them an annularsealed chamv may pass through `suctionpipe 38.

-ber 12 with which the radial bore 88 of collar 95 .is in communication,so that the said chamber may be evacuated by suction pipe 88 in responseThe outer end face of the other drum hub I3 carries a seal casing 13 thesurface of which has diaphragm rings 14 secured to it that extendinwardly toward the adjacent end portion of tubular member 31 upon eachside of a collar 15 secured to said tubular member 31. Seal rings 16 aresecured to the diaphragm rings 14 in contacting relation to the sidefaces of the collar against which they are adapted to slide toveffect aseal therebetween. This arrangement provides a sealed annular chamber 11between the diaphragm rings 14 andy surrounding the adjacent portion ofthe tubular member 31. A radial bore 1B is made in the collar 15 thatopens into chamber 11 and is registered with a hole in the adiacentportion of the tubu1armember31. An elbow coupling 19 has an end threadedinto the hole to establish communication between the annular chamber 11and a suction pipe 80 that is screwed intothe other end of the coupling19. The suction pipe 80 passes through a gland 8| in the closure plateor cap 55 at the end face of the tubular member 31 and leads to thecondenser 51 that is located in advance of the vacuum pump 58 in thesame manner as before described with respect to the suction pipe 68.

'Ihe action of the vacuum pump 5B is to establish a vacuum in theannular chamber 12 in the seal casing 64 carried at the end of trunnionI5,

.and also a vacuum in the annular chamber 11 in the seal casing 13carried at the end of trunnion I4.

The interiors of the seal casings 64 and 13 next to the ends' of therespective trunnions, are in communication with the interior of the drumthrough the annular passageways 43 and 44 that are provided by theclearances 'between the trunnions and the telescoped adjacent tubularmembers that carry the tray 3i. By means of this arrangement, anyvaporized heat transfer material that may seep past the seal rings 1Iand 16, due to an increase of pressure in the drum above the desiredpressure, will be sucked out of the respective chambers 'l2 and 11through the suction pipes 68 and and delivered to the condenser 51..Condensate liquid matter will flow from the condenser into `theaccumulator 49 through a pipe 82 and the volatile, non-condensibles willbe drawn off by the vacuum pump 58 and discharged into the atmosphere..A similar condens-er 51? and pump 58 are provided in communication withthe accumulator 49 through the pipe 82 so as to remove volatilenon-condensibles from the iiuid circuit including the accumulator andboiler. This arrangement provides a blowoil' for the drum and iseilective to clear the drum of abnormal pressure and to discharge thenoncondensible matter at a location remote to the paper making machine.

This invention provides a drier drum construction that is heated with alow pressure hot vapor that is produced outside the drum by subjecting ahigh boiling material in a boiler to heat transfer from high pressure orsuperheated steam. There is a closed fluid circuit in which the drum andthe boiler are interposed, with one side of the iluidcircuitconstituting a drain leading from the drum to the boiler, and the otherside of said fluid circuit providing the means whereby the vaporizedhigh boiling material is delivered to the drum. This arrangement effectsthe continuous revaporization and recirculation of the high boiling heatexchange material. It also provides for the heating of the drum with alow pressure vapor slightly above atmospheric pres-sure but having thetemperature of high pressure steam, without subjecting the walls of thedrum to undesirably high internal pressures.

I claim as my invention:

1. In a drier drum assembly the combination of a rotatable cylinder; aclosed fiuid circuit, in which said cylinder is interposed, for passingvaporized heat transfer material into the cylinder to heat the same, oneside of said uid circuit constituting a drain for said cylinder; astationarily supported tray within said cylinder -With scraper meansattached thereto and extending into close proximity with the innersurface of said cylinder adapted to collect condensate from the innersurface of said cylinder and'deliver the condensate to the drain side ofsaid fluid circuit; means including dipper means supported within saidcylinder and rotatable therewith for collecting condensate from thesurface of the cylinder for delivery to said tray; a heat exchangerexterior to said cylinder col rising a housing interposed in said fluidcircuit to receive condensate from the drain side of said fluid circuit;high boiling low vapor pressure material in said housing; and means forpassing high pressure steam through said housing in heat exchangerelation to the high boiling material to vaporize the material fordelivery to the other side of said fluid circuit; said heat exchangerand said fluid circuit constituting means whereby the high boilingmaterial is continuously revaporized and recirculated through saidcylinder 2. A drier drum comprising a cylinder; hollow trunnions forsupporting and journaling said cylinder for rotation; a tray disposeddiametrically across the interior of said cylinder for receivingcondensate from the inner surface thereof; stationary hollow -supportsextending through the trunnions into the cylinder for maintaining thetray in fixed relation within said cylinder, one of said supportsadapted to drain condensate from said tray; means for dischargingheating vapor through the other of said supports to charge said cylinderwith said vapor; scraper means projecting from said tray into closerelation with the interior surface of said cylinder for -removingcondensate from said interior surface and for discharging the condensateinto said tray; and dipper means mounted in said cylinder adjacent theends thereof and rotatable therewith for collecting condensate of thevapor from the inner surface of the cylinder for discharge to said tray.

3. In a drier drum assembly the combination of a cylinder; hollowtrunnions for supporting and journaling said cylinder for rotation; atray disposed in said cylinder for receiving condensate from the innersurface thereof; hollow stationary supports extending through thetrunnions into said cylinder for maintaining said tray in fixed relationwithin said cylinder, one of said supports adapted to drain thecondensate from said tray; the other of said supports providingcommunication with the interior of said cylinder; means including dippermeans supported Within said cylinder and rotatable therewith forcollecting condensate of the vapor from the surface of said cylinder fordelivery to said tray; a heat exchanger exterior to said cylindercomprising a casing containing high boiling material, and ahlghrpressure steam coil in said casing positioned to be submerged inthe material to vaporize the same; and a conduit establishingcommunication between said casing and said other tray support forcharging the cylinder with the vaporized material.

-maintaining the tray in fixed relation Within said cylinder, saidsupports communicatingwith the interior of said cylinder and one of saidsupports adapted to drain said tray; means including dipper meanssupported within said cylinder and rotatable therewith for collectingcondensate of the vapor from the surface of said cylinder for deliveryto said tray; means exterior to said cylinder for subjecting heattransfer material to high pressure steam to vaporize the material; meansfor delivering the vaporized material through the other of said supportsfor charging the cylinder. with said vaporized material; an exhaust pipeextending inside said cylinder and having an inlet adjacent the topthereof; a pump `for removing vapor from the inside of said cylinderthrough said exhaust pipe; a condenser for condensing the removed vapor;and means for returning the condensed vapor to said fluid circuit. 5. Inadrier drum assembly the combination 0f a Cylinder having end heads;hollow trunnions projecting from said heads for supporting andjournaling said cylinder for rotation; a tray disposed diametricallyacross the interior of said cylinder for receiving condensate from theinner surface thereof; stationary hollow supports yextending through thetrunnions into the cylinder for maintaining the tray in fixed relationwithin f said cylinder, one of said supports adapted to drain condensatefrom said tray; means for dis.- charging heating vapor through the otherof said supports to charge said cylinder with Vapor; and dippers carriedby saidheads in non-contacting relation to the inner surface of thecylinder for removing condensate from said inner surface and depositingthe condensate in said tray.

6. In a drier drum assembly the combination of a cylinder; hollowtrunnions for supporting and journaling said cylinder forl rotation; atray disposed diametrically across the interior of said cylinder forreceiving condensate from the inner surface thereof; means includingdipper means supported within said cylinder and rotatable therewith forcollecting condensate of the vapor from the surface of said cylinder fordelivery to said tray; apertured end walls for said tray, stationaryhollow supports extending through said trunnions into the cylinder formaintaining the tray in fixed relation within said cylinder, one of saidsupports adapted to drain condensate from said tray through one of theapertured end walls, and means for discharging heating vapor through theother of said supports and the other apertured end wall to charge thecylinder with vapor, the said other end wall having its aperture soadapted that the solid portion of said wall provides a dam beneath itsaperture to prevent flow of liquid from the tray into the adjacenthollow support.

. LLOYD HORNBOSTEL.

